By Kevin She
20 Mar 2016
This is the first of a three part article on Cannabis and cannabinoids. Part 2 explores cannabinoids and endocannabinoids as small molecules and Part 3 is a brief overview of cannabinoids and mental health.
Medizinal-Pflantzen 1887 Franz Eugen Köhler
Fig. 1 Flower male and seed-bearing female Cannabis sativa plant
Cannabis sativa is the genus and species name for both hemp, used for fiber and food, and drug-type marijuana used both as a medical drug as well as a recreational drug. In the recreational (and even some medical) market Cannabis is frequently divided into sativa and indica species (or hybrids with purported mixed lineages). However, this distinction is largely a misunderstanding or marketing tactic and a legacy dating back to the earliest days of taxonomic classification. Like officinalis, sativa and indica are species names that were given to many different organisms. Sativa, meaning “common,” was sometimes assigned to species that had been domesticated and cultivated for use by humans (Katz & Weaver 2003). Indica, on the other hand, is from the classical Greek and Latin name for “of India” and was sometimes assigned to species that had been discovered in India. NatureServe Explorer returns 22 organisms containing the name sativa and 28 organisms containing the name indica (and more named sativum or sativus).
The original classification of Cannabis growing in India was made in 1785 by the French biologist Jean-Baptiste Lamarck, of debunked “Lamarckian Inheritance” infamy (Lamarck 1785). Although not strictly true in every case, the highschool biology definition of species is a group of individuals that can interbreed only within that group to produce fertile offspring who are also able to interbreed within that group. For example, Canis lupus includes wolves and dogs, which can interbreed, whereas Canis aureus, the jackal, are a distinct species and cannot interbreed with either wolves or dogs. Since Cannabis is not a special case, by definition – since there can be hybrid sativa and indica strains that can produce viable seeds – this suggests that sativa and indica are the same species.
Incidentally, the almost universal use of “strains” to describe Cannabis is not strictly correct as strain has no official definition of use in botany. Instead, it is used extensively to describe sub-types of microorganisms like bacteria and viruses. The more correct designation of different types of Cannabis would be variety for types that breed true (mature plants grown from seeds generally resemble their parents; these are highly inbred) or cultivar that don’t necessarily breed true and may have to be propagated by cuttings or cloning and must be maintained by people (Bickell 2009). Regardless, “strain” is used widely and extensively to describe different types of Cannabis.
Indeed, modern molecular taxonomic investigation reveal that there are no meaningful genetic differences between strains purported to be sativa and strains purported to be indica (Sawler &al., 2015, Laursen 2015). However, different strains of marijuana do indeed have different properties, arising from differences in their phytochemical profile (the amounts of different small molecules that the plant produces and accumulates) and these differences are influenced by many factors and the sativa/indica classification does not appear to consistently reflect differences in chemical composition (Hazekamp & Fischedick 2012). As such, general claims that sativa or indca strains are “better” for different conditions may not be accurate. See Part 2 for further discussion on cannabinoids and Part 3 for a brief discussion on cannabinoids and mental health.
For completeness’ sake, there is also a variety of Cannabis with a small, spindly, weedy phenotype (appearance) that was assigned the name Cannabis ruderalis – ruderalis being derived from ruderal, which refers to species of plants that are the first to colonize land after a disturbance that removes competing species, such as after a landslide or a wildfire. C. ruderalis has not been studied in sufficient detail to definitively determine its genetic relatedness to C. sativa but there are reports of ruderalis hybrids with other Cannabis strains (Hillig & Mahlberg 2004) and that when cultivated under ideal conditions, instead of in the wild, can grow to heights of 2 meters (yards) or more with similar branch density as other Cannabis strains (Janischevsky 1924).
Fig. 2 Drawing of representative Cannabis plants commonly assigned species names sativa, indica, and ruderalis.
Hemp and marijuana are both members of Cannabis sativa. The main difference between hemp and marijuana is the abundance of the cannabinoid tetrahydrocannabinol (THC); in Canada and in many parts of Europe, hemp is legally defined as Cannabis plants that contain less than 0.3% by weight THC (discussed further in Part 2) and must be one of the registered strains such as Alyssa, Anka, Delores, and Finola, among others. Incidentally, the 0.3% THC limit was somewhat artificially defined by Canadian researcher Ernest Small for the federal government (Small & Marcus 2002).
Industrial hemp associations have taken great pains to promote the distinction that hemp is not marijuana and has no psychoactive properties. Hemp-type Cannabis plants have also been bred to differ from narcotic-type Cannabis in that they tend to grow taller, have a single long central stalk, and has less side branches; all characteristics that maximize the quality and quantity of fibers that can be extracted from a crop of plants.
The primary uses of non-psychoactive hemp are for its fiber – for various applications ranging from paper to textiles and cordage to building materials (hempcrete) – and for the seeds of the female plant for use as food. Hemp has historically been an important source of fiber for clothing and especially for the production of cordage for use in sailing vessels (which was superceded first by “Manila hemp” made from the fibers of the Abacá plant, a relative of the edible banana, which was more resistant to salt water damage which itself was superceded by synthetics).
US Department of Agriculture, Public Domain
Fig. 3 Title card for ‘Hemp for Victory’ a United States WWII era propaganda film encouraging farmers to grow as much hemp as possible to aid in the Allies’ war efforts.
The other major use of hemp is for the production of their seeds, which has been used as a staple food since prehistory. While hemp varieties bred for fiber production can also be used for the production of seeds, there are also varieties that are specialized for seed production that have slightly increased branching leading to increased flower – and seed – production, and seeds that don’t fall off of the plant once mature, similar to most other domesticated seed producing crops. Hemp seeds were considered one of the “five grains” of ancient China that also included barley, rice, wheat, and soybeans (Li 1974). It was also widely cultivated for both fiber and food in the Balkans and in Italy during the Greek and Roman Empires (Fleming & Clarke 1998). Hemp seeds are a complete protein source (it contains all of the essential amino acids) with very high digestibility values (House &al., 2010). Additionally, hemp seed oils are rich in polyunsaturated fatty acids and have an excellent omega-6 to omega-3 fatty acid ratio (3:1) for the promotion of good health (Lesma &al., 2014). Unfortunately, hemp oil has a very low smoke point (165C/330F) compared to grapeseed (216C/420F) (not to be confused with rapeseed, the precursor of canola) or refined sunflower oil (266C/510F).
Despite the hemp industry’s efforts, increasing legalization of both medical and recreational marijuana has created a currently under-regulated “Wild West” environment where unscrupulous merchants are advertising “legal CBD-rich hemp oil.” To further the confusion, some concentrated extracts of medical and narcotic Cannabis are called hash oil and hemp oil can be infused with cannabinoid extracts. CBD (discussed in Part 2) remains a controlled schedule II substance in Canada and a controlled schedule I substance in the United States. Additionally, hemp oil is derived solely from mature seeds which have no appreciable amount of CBD or THC, even when produced from drug-variety Cannabis (Petrovic &al., 2015). Any cannabinoids present in hemp seed oil are contaminants from the flowering parts supporting the seeds; seeds used for commercial oil extraction are washed prior to pressing to remove these contaminants. At best, the only legitimate claim would be “oil derived from CBD-rich hemp plants” where the oil itself contains no CBD. Indeed the United States Food and Drug Administration has issued warning letters to marketers of CBD products only to bar them from making improper medical claims, not that the product contains a controlled substance. In fact, many of the products that were identified for warning contained no detectable amounts of CBD or other cannabinoids.
While literature dates the use of Cannabis sativa to antiquity, the earliest archaeological evidence yet found for the use of hemp fibers dates to around the 5th century BCE in the Yangshao area of China (Kang 1987) and, discovered recently, also around the 5th century BCE in the city of Çatalhöyük in present day Turkey (Hodder 2013). The oldest evidence for the recreational use of the flowers of the Cannabis plant dates to around 700 BCE (Russo &al., 2008); almost two pounds of prepared marijuana flowers was excavated from an ancient and elaborate grave in the Gobi desert. Interestingly, although 2,700 year old recreational marijuana is expected to be a little past its “best before” date, chemical and genetic analysis (Part 2) demonstrate that it was a strain with the potential to have been high in THC – the main psychoactive small molecule in Cannabis. Interestingly, one of the identified gene sequences for THCA synthase, which encodes for the enzyme that ultimately makes THC, is identical to a modern THC synthase.
Cannabis is one of the world’s most recognizable and controversial plants. Due to prohibition, research and economic development of both narcotic and non-narcotic varieties of Cannabis had been suppressed for most of the 20th century due to burdensome requirements for its possession and the difficulty in obtaining research funding. Most investigations that have been authorized were primarily forensic studies to aid law enforcement and social and medical research were mainly restricted to document harmful effects.
With the increasing legalization of both medical and recreational Cannabis in an increasing number of jurisdictions, scientific research with much higher levels of quality than before is possible. The Canadian Consortium for the Investigation of Cannabinoids is spearheading the exciting future of Cannabis research by supporting and promoting evidence-based research in the endocannabinoid system and the therapeutic applications of cannabinoids.
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